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Endurance

Continuous and interval training - update

Brian Mackenzie reviews the pros and cons of interval and continuous training

Continuous training is when an athlete exercises in a steady
aerobic way and interval training is characterised by repetitions of work with
a recovery period following each repetition. Continuous
training can be broken down into the following sub-divisions which have
slightly different effects upon the energy pathways:

Running at 50 to 60% of maximum heart rate or 20 to 36% of V02
Max. Very easy pace, it metabolises fat and is aerobic. Duration 60 minutes
plus. Useful for joggers & ultra distance runners

Running at 60 to 70% of maximum heart rate or 36 to 52% of V02
Max. Slightly faster pace, it burns glycogen and fat and is aerobic. Duration
45 to 90 minutes. Useful for marathon runners. Improves cardiovascular system and capillarisation

Running at 70 to 80% of maximum heart rate or 52 to 68% of V02
Max, 10km pace, it burns glycogen and is aerobic. Duration 30 to 45 minutes.
Useful for 10km and marathon runners. Improves cardiovascular system,
capillarisation and is glycogen burning

Running at 90 to 100% of maximum heart rate or 83 to 99% of
V02 Max. 800/1500m pace, it burns glycogen and is anaerobic. Duration 1 to 5
minutes. Useful for 800 to 5km runners. Improves glycogen burning, lactate
tolerance and removal

Interval Training

Interval running enables the athlete to improve the work load by
interspersing heavy bouts of fast running with recovery periods of slower
jogging. The athlete runs hard over any distance up to 1k and then has a period
of easy jogging.

During the run lactic acid is produced and a state of oxygen debt is reached. During the interval (recovery) the heart and lungs are still
stimulated as they try to pay back the debt by supplying oxygen to help break
down the lactates.

The stresses put upon the body cause an adaptation including
capillarisation, strengthening of the heart muscles, improved oxygen uptake and
improved buffers to lactates. All this leads to improved performance, in
particular within the cardiovascular system.

Before undertaking interval training a few simple rules should be
understood:

Undertake a period of continuous running before starting
Interval running

Consider the various elements of the session and ensure that
they are within the scope of the athlete

The length of the work interval, longer gives a better
effect

The pace should be comfortable raising the athlete's heart
rate to the required % of HRmax(see above)

The number of repetitions should reflect the condition and
age of the athlete

The rest interval should enable the athlete to jog and
bring the heart rate down to near 100 to 110 bpm

Improvements can be made by altering any of the above
variables, however the coach should only change one variable at a time

All changes should be gradual in nature and take place over a
period of time

Ensure the surface to be run on is flat and even. It is usual
to do interval training on a track although it can be done on good quality
grass playing fields. Roads are not a suitable surface because of the pounding
effect

The benefits of interval training

In planning training programs, controversy still exists as to
the optimum duration of the workloads needed to gain maximum results. It would
seem, after all, a waste of effort to train for longer periods than actually
necessary for the same gain in fitness. In an attempt to address this problem,
a research project in Thunder Bay, Ontario, Canada, randomly assigned 21
females, aged between 18 and 26, into two groups before embarking on a
seven-week training programme.

The subjects were tested in a laboratory to evaluate their maximum
oxygen uptake (VO2 max), ventilatory and lactate thresholds, all key indicators
of aerobic fitness. All the subjects trained at 85% of VO2 max for the first two
weeks, with a 5% increase every fortnight. Thus, they trained at 85% for the
first fortnight, 90% for the second fortnight and 95% for the third. The
frequency of training, which continued to exhaustion, was four times each week.
Group one trained with 30 second interval workloads, while group two used a two
minute workload. Both groups, however, continued with a work to recovery ratio
of 1:1.

At the end of the seven week training programme, the subjects were
retested in the laboratory. It was discovered that there was a significant
increase in VO2 max, ventilatory threshold and lactate thresholds of all
subjects. There was, however, no significant difference between the two groups
utilising the different workload durations.

This might suggest that there is little difference in using 30
second or two minute duration workloads, while both forms of workout have
strong training effects for aerobic fitness.

The study does not, however, state the initial fitness levels of
the subjects, which clearly has an effect upon the possible gains in fitness
achievable. Further, the training does not mimic a realistic training
programme, where utilisation of different energy pathways should be involved,
including the important steady state component of training.

About the Author

Brian Mackenzie is a British Athletics level 4 performance coach and a coach tutor/assessor. He has been coaching sprint, middle distance and combined event athletes for the past 30+ years and has 45+ years experience as an endurance athlete.

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